We have been evaluating latest type alloy water pumps as some racers and engine builders have been experiencing cavitation or air bubbles in the engine.

The 0riginal alloy airtex pump Rover supplied (tooling scrapped) was a good pump with Koyo high quality bearing and pumped consistently from about 2000rpm.

Some mini owners who change their radiators still have hot running engines and then have the problem of trying to solve the cause. Checking the thermostat, radiator cap, cylinder head for cracks or to high a compression ratio which can all cause overheating are usually first on the list after all other plumbing has been scrutinized, but the water pump often gets overlooked.

The water pump should have the same increase in flow rate of water at all times from 1000rpm upwards.
If a pump is not made dimensionally correct consistently, cavitation may occur.
Cavitation simply explained is small air bubbles that grow and then collapse.

The violent collapse of air bubbles causes shock waves to be radiated through the water in an effect commonly associated with ultrasonics. This causes extreme temperatures and pressures.
Mini Spares have sourced a water pump manufacturer in the UK that has testing facilities and with modern day designs they have evolved a new range of alloy Evolution pumps with correct increase of flow rate at all rpm.

The new design pumps are 130 gramms lighter than our standard pumps by virtue of a strong lightweight impellor made of a glass filled plastic known as PPS, which is more accurate in its form and gives increased efficiency due to its weight and is used by Jaguar and Aston Martin.

The impeller and pump were tested pumping coolant to 10,000 RPM without any detriment to the PPS impeller these pumps will survive in most A series blocks.

A modern triple lip seal and top brand bearing are used rather than the old single style seal.
These super pumps are more expensive but carry a 3 year guarantee .